1. Field of the Invention
The present invention relates to a heat sink/circuit board assembly, which comprises a combination of a circuit board with heat-generating parts mounted thereon and a heat sink for heat radiation.
2. Description of Background Information
In electronic apparatuses using heat-generating parts such as a power transistor, which radiate relatively high heat when electric current flows, it is necessary to prevent impairment of the heat-generating parts itself by the heat or damaging other peripheral components due to thermal influence. For such a reason, the arrangement as shown in FIG. 1 has been devised.
In FIG. 1, a circuit board 32 on which a heat-generating part 31 comprising a power transistor is mounted is connected with a main heat sink 33 with a recessed portion 33a near the edge of the opening of the recessed portion through a sub-heat sink 34 of block type, which directly contacts with the heat-generating parts. On the lower surface of the circuit board 32, i.e. on the main surface opposite to the parts mounting surface where heat-generating parts 31 are mounted, printed circuit is provided, and the heat-generating parts 31 are electrically connected to the printed circuit together with the other electronic components (not shown) on the circuit board. Small screws are used to connect between the heat-generating parts 31 and the sub-heat sink 34 as well as between the sub-heat sink 34 and the main heat sink 33.
In the conventional type heat sink/circuit board assembly as described above, the positions of the heat-generating parts 1 and the other electronic components must be confirmed during inspection or repair of the circuits and parts using a tester 36 as shown in FIG. 2, and it is necessary to remove the main heat sink 33, which covers each of these components, from the other components and parts.
As the result, the circuit must be operated under the condition where only sub-heat sink 34 is connected to the heat-generating parts 31. Thus, it is difficult to sufficiently radiate the heat, and there is a possibility that the heat-generating parts 31 or peripheral components may be damaged by heat.